SN 2010mc (Fabruary 2013)

Eran Ofek and collaborators reported that this core collapse supernova had an outburst one month before explosion. The total energy (kinetic energy of the ejected mass and radiation) and duration of the pre-explosion outburst (PEO) are similar to several other outbursts that are termed Intermediate Luminosity Optical Transients (ILOT). See this updated Energy-Time Diagram.

I suggest that the PEO was energized by gravitational energy released by mass accreted onto an O star main sequence companion. The source of the mass is the envelope of the primary star (the one that exploded) that experienced a rapid expansion before explosion. The expansion was triggered by the powerful nuclear burning of oxygen in the core in moths before explosion.